A multiple-probe, multiple-baseline, across-subjects design was used to examine the writing performance of four low-achieving adult students with and without disabilities enrolled in general equivalency diploma (GED) preparatory classes. Students' writing was evaluated before instruction and after self-regulated strategy development (SRSD) instruction for the POW (Pick my idea-pay attention to the prompt, Organize, Write and say more) + TREE (Topic sentence, Reasons, Explanations, Ending) + COPS (Capitalize, Organize, Punctuate, Sense) strategies. Results following the instruction indicated that students had learned to independently write expository essays. The number of essay parts and transition words increased, demonstrating evidence of organized essays. The number of words written and descriptive word use also increased. Gains were maintained on maintenance probes. All students who took the GED exam passed the essay-writing portion following the intervention. (Contains 3 figures and 2 tables.)